The prevalence of frontotemporal dementia
Ratnavalli E, Brayne C, Dawson K, Hodges JR. ;
Commented by , 20 Aug 2002
Aim of the study
Estimate the prevalence of fronto-temporal dementia (FTD) and other degenerative early-onset dementias in a geographically defined population.
Method
Case ascertainment by review of case records of three specialist clinic database and inpatient admissions at a university hospital in Cambridge, UK, for patients with dementia who were <65 years of age living in a defined geographical area on may 30, 2000.
The diagnosis of various dementias was based on published criteria. The 1988 population estimates for the area were used to calculate age and sex prevalence with confidence intervals for AD, FTD and other causes of dementia.
Results
Out of 108 patients with early onset dementia, 60 were <65 on census date, giving an overall prevalence of 81 (95% CI, 62.8 to 104.5) per 100,000 in the 45- to 64-year age group.
The prevalence of FTD and AD was the same (15 per 100,000) in that population. The mean age of onset of FTD was 52.8 with a striking male preponderance (14:3).
Discussion
Despite the limitations of the ascertainment method with small N and limited geographical representation, these data reveal that FTD is a more common cause of early-onset dementia that previously recognized, and may be more common in men, contrary to the traditional belief.
A companion editorial by Galasko and Marder (Neurology 2002; 58: 1585-1586) and two original articles by Rosen et al (Neurology 2002; 58: 1608-1615) on the utility of clinical criteria to distinguish FTD from AD, and by Riemenschneider et al (Neurology 2002; 58: 1622-1628) on protein markers in CSF associated with FTD make this issue of Neurology a remarkable cluster of articles on this important cause of dementia.